If I can jump in here, I too tried five different nausea meds until out of frustration my oncologist put me on Larazepam, which basically fogged me at night so I could rest. Mind you this was for the radiation sickness only as I did not have Chemo at that time. Everyone reacts to radiation differently. Radiation to the head and neck seems far worse than most.
There just isn't a lot to comfort your husband. But remember, this sickness isn't forever, just for a while. By spring things will look better and that's not far away. It isn't a pleasant fight by any means but it does take courage.